As disclosed in commonly assigned U.S. Pat. No. 5,296,887, recently developed cartridges for strips of photographic film have been designed to enclose a multi-part spool onto which the film strip is wound. FIGS. 1 and 2 of the present specification illustrate such a spool 10 which can be assembled using the apparatus and method of our invention. The central core or arbor 12 of the spool includes features for attachment of a film strip by rotating core 12 about its longitudinal axis 12'. Near one end of core 12, a large end flange 14 is provided which is axially spaced a small distance from a plurality of radially protruding, circumferentially spaced retainer tabs or protuberances 16. Rather than tabs 16, a complete annular retaining flange could be used. At least three tabs 16 are used, though as many as six may be preferable. To prevent a wound strip from telescoping along core 12, and for other purposes, a flexible, ranged end disk 18 is provided having a central opening 18' sized to fit core 12 between tabs 16 and flange 14. Near the other end, a small end flange 20 similarly is provided which is spaced axially a small distance from a plurality of radially protruding, circumferentially spaced retainer tabs or protuberances 22. Again, three to six such tabs are used, or an annular retaining flange. A flexible, ranged end disk 24 is provided having a central opening 24' sized to fit core 12 between tabs 22 and flange 20. End disks 18, 24 may be made from a suitable plastic material and may have a thickness of about 0.006 inch (0.152 mm), thus permitting the material surrounding openings 18', 24' to flex sufficiently to allow the disks to be installed past tabs 16, 22.
A spool having this design must be assembled precisely and rapidly for efficient manufacture of the associated photographic film product. The disks must be installed without damage. Merely pushing disks 18, 24 straight along core 12 and forcing them over tabs 16, 22, respectively, risks unacceptable deformation of the disks as they must then flex to clear all of the tabs more or less simultaneously. Proper and improper installation of the disks must somehow be detectable to ensure that no defective spools are supplied for use in a final product. While manual assembly and verification are possible, the rate of production would be too slow for efficient manufacture.